This invention relates to an image sensing method and apparatus and, more particularly, to an image sensing method and apparatus capable of achieving better resolution by using CCD, or the like, as two dimensional solid image sensing elements and by displacing a focal point of an object in two directions in a space area.
As a most well-known method of reproducing a color image by using a single piece of image sensing element, there is a method in which an image sensing element output signal, made by superposing a color carrier signal having half of a pixel sampling frequency on a brightness signal component. The signal is picked up by providing complementary color filters arranged in mosaic fashion on photo sensors of the image sensing element. The color information is obtained by Y/C separation of the image sensing element output signal. This method is widely applied to video cameras for personal use, and is very effective in providing inexpensive cameras.
Further, regarding an image sensing apparatus such as video camera using CCD, or the like, improvement of spatial resolution has been demanded. Especially, as a method to realize the improvement of the spatial resolution without simply increasing pixel density of CCD, there have been proposed some methods to improve apparent resolution. For example, Japanese Patent Application Laid Open No. 64-69160 discloses a method of displacing a CCD in the horizontal and vertical directions by using a piezoelectric element, and Japanese Patent Application Laid Open No. 63-284979 discloses a method of using optical path displacement mechanism provided between an image sensing lens group and a CCD.
However, in the aforesaid conventional examples, the frequency of a color carrier signal representing color information is only half of pixel sampling frequency, thus, it is theoretically impossible to reproduce high resolution color information. Therefore, although a single image sensor type image sensing apparatus is compact and inexpensive, it is not sufficient to use the obtained image when better image quality than those taken by a conventional personal use video camera is required.
Furthermore, in the aforesaid conventional image sensing apparatus, to simply improve resolution of the CCD itself is emphasized, and there lacks consideration regarding color signal processing. As a result, resolution of a black and white signal can be improved because of the improvement of resolution of the CCD, however, the improvement of resolution of the CCD does not directly contributes to improve resolution of a color image taken by a single image sensor type color video camera, which has been widely spread for personal use.